Photoacoustic image generation apparatus and insert

ABSTRACT

There are provided a photoacoustic image generation apparatus and an insert that separately acquire both positional information and surrounding environment information of the insert. A puncture needle is at least partially inserted into a subject. An optical fiber guides light with a first wavelength and light with a second wavelength which are incident while being switched. The light guided by the optical fiber is emitted from a light emitting portion. A light absorption member absorbs the light with the first wavelength emitted from the light emitting portion, generates photoacoustic waves, and transmits the light with the second wavelength emitted from the light emitting portion.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of International Application No. PCT/JP2016/003035, filed on Jun. 23, 2016, which is incorporated herein by reference in its entirety. Further, this application claims priority from Japanese Patent Application No. 2015-131068, filed on Jun. 30, 2015, the disclosure of which is incorporated by reference herein in its entirety.

BACKGROUND Technical Field

The present invention relates to a photoacoustic image generation apparatus, and more particularly, to a photoacoustic image generation apparatus that detects photoacoustic waves generated by the absorption of light by a light absorber and generates a photoacoustic image.

In addition, the invention relates to an insert such as a puncture needle used in the photoacoustic image generation apparatus.

Related Art

An ultrasonography method has been known as a kind of image inspection method that can non-invasively inspect the internal state of a living body. In ultrasonography, an ultrasound probe that can transmit and receive ultrasonic waves is used. In a case in which the ultrasound probe transmits ultrasonic waves to a subject (living body), the ultrasonic waves travel in the living body and are reflected from the interface between tissues. The ultrasound probe receives the reflected ultrasonic waves and a distance is calculated on the basis of the time until the reflected ultrasonic waves return to the ultrasound probe. In this way, it is possible to capture an image indicating the internal aspect of the living body.

In addition, photoacoustic imaging has been known which captures the image of the inside of a living body using a photoacoustic effect. In general, in the photoacoustic imaging, the inside of the living body is irradiated with pulsed laser light such as a laser pulse. In the inside of the living body, a living body tissue absorbs the energy of the pulsed laser light and ultrasonic waves (photoacoustic waves) are generated by adiabatic expansion caused by the energy. For example, an ultrasound probe detects the photoacoustic waves and a photoacoustic image is formed on the basis of a detection signal. In this way, it is possible to visualize the inside of the living body on the basis of the photoacoustic waves.

For the photoacoustic imaging, JP2015-37519A discloses a technique in which light emitted from a light source is guided to the vicinity of a leading end of a puncture needle by, for example, an optical fiber and is emitted from the leading end to a photoacoustic wave generation portion of the puncture needle. The photoacoustic wave generation portion includes, for example, a light absorption member. JP2015-37519A discloses a technique in which the light absorption member can be made of, for example, an epoxy resin, a polyurethane resin, or a fluorine resin with which a black pigment is mixed, silicon rubber, or a black paint having high light absorbance with respect to the wavelength of laser light. In addition, JP2015-37519A discloses a technique in which a metal film or an oxide film having light absorptivity with respect to the wavelength of laser light is used as the light absorption member. An ultrasound probe detects the photoacoustic waves generated by the emission of light to the photoacoustic wave generation portion and a photoacoustic image is generated on the basis of a detection signal of the photoacoustic waves. In the photoacoustic image, a part of the photoacoustic wave generation portion appears as a bright point, which makes it possible to check the position of the puncture needle using the photoacoustic image.

Furthermore, JP2013-13713A discloses a puncture needle including a light emitting portion. In JP2013-13713A, light emitted from a light source is guided to the light emitting portion of the puncture needle by, for example, an optical fiber and is emitted from the light emitting portion to the outside. In a subject, photoacoustic waves are generated due to the absorption of the light emitted from the light emitting portion. An ultrasound probe detects the photoacoustic waves generated by the absorption of the light emitted from the light emitting portion of the puncture needle and a photoacoustic image is generated on the basis of the detection signal of the photoacoustic waves. In this way, it is possible to check the position of the puncture needle.

SUMMARY

Here, for example, in a case in which the puncture needle is inserted into a blood vessel, an operator can determine whether the leading end of the puncture needle has been inserted into the blood vessel, on the basis of whether blood has flowed into the needle or a base portion of the needle. However, in JP2015-37519A and JP2013-13713A, since the light guide member, such as an optical fiber, passes through the needle, the inflow path of blood is narrower than that in a case in which, for example, the optical fiber is not provided. Therefore, it takes time for the inflow of blood and it takes time to determine whether the leading end of the puncture needle has been inserted into the blood vessel.

In JP2015-37519A, the light absorber provided at the leading end of the needle generates photoacoustic waves and the light absorber absorbs almost all of the light emitted to the photoacoustic wave generation portion. Therefore, even in a situation in which the light absorber is present in front of the needle in a needling direction in the subject, it is difficult for the light absorber to generate photoacoustic waves. For this reason, in JP2015-37519A, only the positional information of the leading end of the needle can be acquired and it is difficult to acquire surrounding environment information such as information indicating whether the light absorber is present in the vicinity of the needle. In contrast, in JP2013-13713A, the light absorber that is present in front of the needle in the needling direction in the subject is irradiated with the light emitted from the light emitting portion. Therefore, in a case in which light with a wavelength absorbed by blood (blood vessel) is emitted from the light emitting portion, it is possible to determine whether the leading end of the needle has been inserted into the blood vessel on the basis of whether a bright point is present in the photoacoustic image.

However, in JP2013-13713A, the photoacoustic waves generated by the absorption of the light emitted from the light emitting portion by, for example, metal forming a puncture needle main body are detected in addition to the photoacoustic waves generated by the absorption of the light emitted from the light emitting portion by the light absorber that is present in front of the needle in the needling direction in the subject. In this case, since there are two photoacoustic wave generation sources, two bright points are mixed in the photoacoustic image. Since the intensity of the detected photoacoustic waves is sequentially changed by the movement of the body or the movement of the probe, a bright point blinks in the photoacoustic image. In JP2013-13713A, since two bright points blink independently, it is difficult to distinguish the portion indicating the positional information of the puncture needle from the portion indicating the surrounding environment information in the photoacoustic image. This problem is not limited to the puncture needle and may also occur in a case in which the position and surrounding environment information of other inserts to be inserted into the subject, such as catheters or guide wires, are acquired by a photoacoustic image.

The invention has been made in view of the above-mentioned problems and an object of the invention is to provide a photoacoustic image generation apparatus that can separately acquire both the positional information and surrounding environment information of an insert.

In addition, an object of the invention is to provide an insert that is used in the photoacoustic image generation apparatus.

In order to achieve the objects, the invention provides an insert that is at least partially inserted into a subject. The insert comprises: a light guide member that guides light with a first wavelength and light with a second wavelength different from the first wavelength which are incident while being switched; a light emitting portion from which the light guided by the light guide member is emitted; and a light absorption member that absorbs the light with the first wavelength emitted from the light emitting portion, generates photoacoustic waves, and transmits the light with the second wavelength emitted from the light emitting portion.

In the insert according to the invention, preferably, the light absorption member covers at least a part of the light emitting portion.

Preferably, the light absorption member includes a light absorber that absorbs the light with the first wavelength and transmits the light with the second wavelength and a resin including the light absorber.

The insert according to the invention may have an inner cavity. The light absorption member may function as a fixing member that fixes the light guide member to an inner wall of the inner cavity.

The insert according to the invention may further include a transparent resin that transmits at least the light with the second wavelength. The light absorption member may be covered with the transparent resin. In a case in which the insert has an inner cavity, the light guide member and the light absorption member may be fixed to an inner wall of the inner cavity of the insert by the transparent resin.

The insert according to the invention may be a puncture needle having an inner cavity. In this case, the insert may further include a hollow tube in which the light guide member is accommodated.

The puncture needle may include an inner needle and an outer needle. The inner needle may include the hollow tube. The inner needle may seal at least a portion of the inner cavity of the puncture needle.

The light absorption member may function as a fixing member that fixes the light guide member to an inner wall of the hollow tube.

The insert according to the invention may further include a transparent resin that transmits at least the light with the second wavelength. The light guide member and the light absorption member may be fixed to an inner wall of the hollow tube by the transparent resin.

The insert according to the invention may further include a phosphor that converts the light with the second wavelength emitted from the light emitting portion into light with a third wavelength different from the first wavelength and the second wavelength.

Preferably, the insert further includes an optical connector that detachably connects the light guide member and an optical fiber which guides the light with the first wavelength and the light with the second wavelength emitted from a light source.

The invention provides a photoacoustic image generation apparatus comprising: a first light source that emits light with a first wavelength; a second light source that emits light with a second wavelength different from the first wavelength; an insert that is at least partially inserted into a subject and comprises a light guide member that guides the light with the first wavelength and the light with the second wavelength which are incident while being switched, a light emitting portion from which the light guided by the light guide member is emitted, and a light absorption member that absorbs the light with the first wavelength emitted from the light emitting portion, generates photoacoustic waves, and transmits the light with the second wavelength emitted from the light emitting portion; acoustic wave detection means for detecting first photoacoustic waves which are generated by the absorption of the light with the first wavelength by the light absorption member and second photoacoustic waves which are generated in the subject due to the light emitted from the light emitting portion; and photoacoustic image generation means for generating a first photoacoustic image on the basis of the first photoacoustic waves and generating a second photoacoustic image on the basis of the second photoacoustic waves.

In the photoacoustic image generation apparatus according to the invention, the second photoacoustic waves may be generated by the absorption of the light with the second wavelength transmitted through the light absorption member by the subject.

The insert may further include a phosphor that converts the light with the second wavelength emitted from the light emitting portion into light with a third wavelength different from the first wavelength and the second wavelength. In this case, the second photoacoustic waves may be generated by the absorption of the light with the third wavelength emitted from the phosphor by the subject.

The acoustic wave detection means may further detect reflected acoustic waves with respect to acoustic waves transmitted to the subject. In this case, the photoacoustic image generation apparatus according to the invention may further comprise reflected acoustic image generation means for generating a reflected acoustic image on the basis of the reflected acoustic waves.

The photoacoustic image generation apparatus according to the invention may further comprise image combination means for combining at least one of the first photoacoustic image or the second photoacoustic image and the reflected acoustic image.

The photoacoustic image generation apparatus and the insert according to the invention can separately acquire both the positional information and surrounding environment information of the insert.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating a photoacoustic image generation apparatus according to a first embodiment of the invention.

FIG. 2 is a perspective view illustrating the vicinity of a leading end of a puncture needle.

FIG. 3 is a graph illustrating an example of an absorption spectrum of a light absorption member.

FIG. 4 is a cross-sectional view illustrating the vicinity of a leading end of a puncture needle according to a modification example.

FIG. 5 is a flowchart illustrating the procedure of an operation of the photoacoustic image generation apparatus.

FIG. 6 is a flowchart illustrating the procedure of a first photoacoustic image generation process.

FIG. 7 is a flowchart illustrating the procedure of a second photoacoustic image generation process.

FIG. 8 is a flowchart illustrating the procedure of an ultrasound image generation process.

FIG. 9 is a graph illustrating the absorbance-wavelength characteristics of a phosphor.

FIG. 10 is a graph illustrating the emission intensity-wavelength characteristics of the phosphor.

FIG. 11 is a cross-sectional view illustrating the vicinity of a leading end of a puncture needle according to a third embodiment of the invention.

FIG. 12 is a cross-sectional view illustrating the vicinity of a leading end of a puncture needle according to a modification example.

DESCRIPTION OF EMBODIMENTS

Hereinafter, embodiments of the invention will be described in detail with reference to the drawings. FIG. 1 illustrates a photoacoustic image generation apparatus according to a first embodiment of the invention. A photoacoustic image generation apparatus 10 includes a probe (ultrasound probe) 11, an ultrasound unit 12, a first light source (laser unit) 13, a second light source (laser unit) 14, and a puncture needle 15. In the embodiment of the invention, ultrasonic waves are used as acoustic waves. However, the invention is not limited to the ultrasonic waves. Acoustic waves with an audible frequency may be used as long as an appropriate frequency can be selected according to, for example, an inspection target or measurement conditions.

The first light source 13 emits light with a first wavelength. The second light source 14 emits light with a second wavelength. For example, the first light source 13 and the second light source 14 emit pulsed light with a pulse energy of about 0.3 μJ to 30 μJ and a pulse time width of about 1 ns to 100 ns. The first wavelength and the second wavelength are different from each other. The first light source 13 and the second light source 14 are, for example, solid-state laser light sources. The type of light source is not particularly limited. The first light source 13 and the second light source 14 may be laser diode light sources (semiconductor laser light sources) or light amplifying laser light sources having a laser diode light source as a seed light source. In addition, light sources other than the laser light source may be used.

The first light source 13 and the second light source 14 are switched and used. In a case in which the first light source 13 emits the light with the first wavelength, the second light source 14 does not emit the light with the second wavelength. On the contrary, in a case in which the second light source 14 emits the light with the second wavelength, the first light source 13 does not emit the light with the first wavelength.

The light with the first wavelength emitted from the first light source 13 and the light with the second wavelength emitted from the second light source 14 are incident on a wavelength division multiplexing coupler 18 through, for example, light guide means such as an optical fiber 17. The wavelength division multiplexing coupler 18 multiplexes the light with the first wavelength and the light with the second wavelength and emits the multiplexed light to one optical fiber. Light emitted from the wavelength division multiplexing coupler 18 is guided to the puncture needle 15 by a light guide member such as an optical fiber 19. Instead of the multiplexing using the wavelength division multiplexing coupler 18, the light with the first wavelength and the light with the second wavelength may be multiplexed by a dichroic mirror that transmits one of the light with the first wavelength and the light with the second wavelength and reflects the other light. Specifically, the dichroic mirror may be provided in a case of an optical system and the light with the first wavelength and the light with the second wavelength may be multiplexed by the dichroic mirror and may be incident on one optical fiber.

The puncture needle 15 is a needle that is inserted into the subject. The optical fiber 19 is inserted into the puncture needle 15. An optical connector 20 is provided between the wavelength division multiplexing coupler 18 and the optical fiber 19. The optical connector 20 detachably connects the optical fiber 19 and an optical fiber that extends from the wavelength division multiplexing coupler 18. The connection of the optical connector 20 is released to throw away the optical fiber 19 together with the puncture needle 15 at the same time.

FIG. 2 illustrates the vicinity of a leading end of the puncture needle 15. The puncture needle 15 has a light absorption member 51 provided in the vicinity of the leading end. The light absorption member 51 absorbs the light with the first wavelength emitted from a light emitting portion 19 a and generates photoacoustic waves. The light absorption member 51 is provided in the vicinity of the leading end of the puncture needle 15 and can generate photoacoustic waves at a point in the vicinity of the leading end of the puncture needle 15. Since the length of the generation source (sound source) of the photoacoustic wave is sufficiently smaller than the total length of the puncture needle, the sound source can be regarded as a point sound source. In addition, the light absorption member 51 does not absorb the light with the second wavelength and transmits the light with the second wavelength to the outside of an opening portion provided at the leading end of the puncture needle 15. In a case in which the wavelength of light emitted from the light emitting portion 19 a is equal to the second wavelength, the light absorption member 51 does not generate photoacoustic waves since it does not absorb the light with the second wavelength.

The leading end (a far end as viewed from the light source side) of the optical fiber 19 forms the light emitting portion 19 a from which guided light is emitted. The light emitting portion 19 a is provided in the vicinity of the leading end of the puncture needle 15. The optical fiber 19 guides the light with the first wavelength and the light with the second wavelength, which are switched and are incident from the light source side, to the vicinity of the leading end of the puncture needle 15. Here, “the vicinity of the leading end” means a position where the light absorption member 51 provided at the leading end can generate photoacoustic waves capable of imaging the position of the leading end of the puncture needle 15 with accuracy required for a needling operation in a case in which the light emitting portion 19 a is disposed at the position. For example, the vicinity of the leading end is the range of 0 mm to 3 mm from the leading end to the base end of the puncture needle 15. The optical fiber 19 may be coated. For example, polyimide, a fluorine resin, or an acrylic resin may be used for coating.

In a case in which the light absorption member 51 transmits the light with the second wavelength, the light absorption member 51 does not need to absorb all of the light with the second wavelength. That is, the light absorbance of the light absorption member 51 does not need to be 0%. The light absorption member 51 may absorb and transmit the light with the second wavelength at a ratio of, for example, about 1:9. Similarly, in a case in which the light absorption member 51 absorbs the light with the first wavelength, the light absorption member 51 does not need to absorb all of the light with the first wavelength, that is, the light absorbance of the light absorption member 51 needs to be 100%. The light absorption member 51 may absorb and transmit the light with the first wavelength at a ratio of, for example, about 9:1. The same description holds for the transmission of the light with the second wavelength and the absorption of the light with the first wavelength or light with a third wavelength which will be described below.

The light absorption member 51 may cover at least a part of the light emitting portion 19 a. In addition, the light absorption member 51 may also function as a fixing member that fixes the optical fiber 19 to an inner wall of an inner cavity of the puncture needle 15.

The light absorption member 51 includes, for example, a light absorber that absorbs the light with the first wavelength and transmits the light with the second wavelength and a resin such as an epoxy resin including the light absorber. For example, in a case in which a pulsed laser diode with a wavelength of 905 nm is used as the first light source 13, a material that absorbs light with the wavelength is mixed as the light absorber with a resin. For example, the following material can be used as the light absorber: YKR-2900 or YKR-2081 which is a phthalocyanine-based material manufactured by Yamamoto Chemical Industry Co., Ltd.; FDN-004 or FDN-005 manufactured by Yamada Chemical Co., Ltd.; a cyanine-based absorber material disclosed in JP5243056B; IRA908, IRA912, or IRA931 manufactured by Exciton Inc.; or S0433 manufactured by FEW Chemicals GmbH. In a case in which these absorbers are used, a pulsed laser diode with a wavelength of 870 nm may be used as the first light source 13.

In a case in which a resin including the above-mentioned absorber is used as the light absorption member 51, light with a wavelength of 905 nm emitted from the first light source 13 is converted into acoustic waves. The acoustic waves can be used to detect the position of the leading end of the puncture needle 15. In contrast, light emitted from the second light source 14 is transmitted through the light absorption member 51 and is emitted to the outside of the puncture needle 15. The light can be used to evaluate the surrounding environment of the leading end portion of the puncture needle 15. The wavelength of the light emitted from the second light source 14 can be appropriately selected from a wavelength range in which absorbance is low in the absorbance-wavelength characteristics of the absorber.

FIG. 3 illustrates an example of the absorption spectrum of the light absorption member 51. The horizontal axis indicates a wavelength and the vertical axis indicates absorbance. A cyanine-based absorber material is used as the absorber included in the light absorption member 51. In the light absorption member 51, the absorbance of light with a wavelength of about 905 nm is the highest and the absorbance of light is rapidly reduced toward a long wavelength side and a short wavelength side. In a case in which the light absorption member 51 is used, the wavelength of the light emitted from the second light source 14 may be appropriately selected from the range of 400 nm to 650 nm or the range of 1000 nm or more.

The second wavelength is set according to materials around the part into which the puncture needle 15 is inserted. In other words, the second wavelength is set according to an evaluation target material in the surrounding environment of the puncture needle 15. A light source emitting light with a wavelength which is absorbed by an evaluation target material to generate photoacoustic waves is used as the second light source. For example, in a case in which the evaluation target is blood (blood vessel), a light source that emits light with a wavelength of 530 nm is used as the second light source 14. In a case in which the evaluation target is a nerve, a light source that emits light with a wavelength of 1210 nm is used as the second light source 14.

In a case in which the evaluation target is a contrast agent used to visualize, for example, a lymph node or a lymph tube, a light source emitting light with a wavelength which is absorbed by the contrast agent to generate photoacoustic waves may be used as the second light source 14. For example, in a case in which indocyanine green (ICG) is used as the contrast agent, a light source that emits light with a wavelength of 780 nm may be used as the second light source 14. In a case in which methylene blue is used as the contrast agent, a light source that emits light with a wavelength of 663 nm may be used. In a case in which Patent Blue V is used as the contrast agent, a light source that emits light with a wavelength of 638 nm may be used.

In a case in which a specific material is transferred to a cancer cell by a drug delivery system (DDS) and it is evaluated whether the material is present, a light source emitting light with a wavelength which is absorbed by the material to generate photoacoustic waves may be used as the second light source 14. For example, in a case in which the evaluation target is a gold nanoparticle, a light source that emits light in the wavelength range of 600 nm to 900 nm according to the diameter of the gold nanoparticle may be used as the second light source 14. In a case in which the evaluation target is a carbon nanotube, a light source that emits light in the wavelength range of 670 nm to 820 nm may be used as the second light source 14.

The first light source 13 and the second light source 14 are not necessarily independent light sources which are separated from each other. One light source that can emit light components with a plurality of wavelengths may be used to emit the light with the first wavelength and the light with the second wavelength such that the light components are switched. An example of the light source that can emit light components with a plurality of wavelengths including the first wavelength (905 nm) is a Ti:Sf laser or a Nd:YAG-optical parametric oscillation (OPO) laser. In this case, the multiplexing means, such as the wavelength division multiplexing coupler or the dichroic mirror, can be omitted.

The second light source 14 does not need to be one light source. The second light source 14 may include two or more light sources. For example, the photoacoustic image generation apparatus 10 may include, as the second light source 14, a light source that emits light with a wavelength of 530 nm and a light source that emits light with a wavelength of 1210 nm. In this case, the user may select which of the light sources in the second light source 14 is to be used to emit light according to the evaluation target. Specifically, in a case in which the evaluation target is blood (blood vessel), a light source that emits light with a wavelength of 530 nm may be selected to emit light. In a case in which the evaluation target is a nerve, a light source that emits light with a wavelength of 1210 nm may be selected to emit light. For example, a menu for selecting an evaluation target may be provided on a menu screen such that the user can select the light source to be used to emit light.

In a case in which the second light source 14 includes two or more light sources, two or more light sources may be controlled such that they emit light in time series while being switched. In this case, each light source may emit light, photoacoustic waves (second photoacoustic waves) may be detected, and second photoacoustic images corresponding to light components with each wavelength may be generated. In this case, the second photoacoustic images corresponding to light components with each wavelength are displayed while being switched or are displayed side by side such that a plurality of types of evaluation targets can be evaluated.

The second light source 14 is not necessarily a light source that emits light with a single wavelength and may be a light source that can emit light components with a plurality of wavelengths while switching the light components. For example, OPO may be used for the second light source 14. The OPO may be performed in a broad band and light with an arbitrary wavelength may be dispersed in the broad band to select a wavelength. In addition, the second light source 14 may emit light components with a plurality of wavelengths different from the first wavelength while switching the light components and photoacoustic waves corresponding to the light components may be detected. Then, the relationship between the wavelength and the intensity of the detected photoacoustic waves may be calculated to evaluate a surrounding environment. The surrounding environment may be evaluated to evaluate melanin (metastatic malignant melanoma), to monitor a cauterized state, to monitor tissue death caused by ethanol infusion, to detect nerve peaks, to evaluate the behavior of artheroma plaque, to evaluate liver fibrosis (scattering), and to evaluate the degree of progress of inflammation.

The puncture needle 15 may include a transparent resin that transmits at least the light with the second wavelength. FIG. 4 is a cross-sectional view illustrating the leading end portion of the puncture needle 15 including the transparent resin. A transparent resin 52 transmits at least the light with the second wavelength. The transparent resin 52 may transmit most of incident light with the second wavelength and does not need to transmit all of the incident light with the second wavelength. That is, the transparent resin 52 does not need to transmit 100% of the light with the second wavelength. For example, an epoxy resin (adhesive) is used as the transparent resin 52. For example, a thermosetting resin, an ultraviolet-curable resin, or a photocurable resin is used as the transparent resin 52.

A puncture needle main body 151 forming a main body portion of the puncture needle 15 has an inner cavity. The transparent resin 52 covers the light absorption member 51 in the inner cavity of the puncture needle main body 151. The transparent resin 52 may cover the optical fiber 19 in the inner cavity of the puncture needle main body 151. The transparent resin 52 may function as a fixing member that fixes the light absorption member 51 and the optical fiber 19 to the inner wall of the puncture needle main body 151. In FIG. 4, the light absorption member 51 covers a light emitting portion 19 a of the optical fiber 19 and (the leading end portion of) the optical fiber 19 and the light absorption member 51 are fixed to the inner wall of the puncture needle main body 151 by the transparent resin 52.

Returning to FIG. 1, the probe 11 includes, for example, a plurality of detector elements (ultrasound oscillators) which are acoustic wave detection means and are one-dimensionally arranged. After the puncture needle 15 is inserted into the subject, the probe 11 detects the photoacoustic waves generated from the light absorption member 51 (see FIG. 2). The probe 11 performs the transmission of acoustic waves (ultrasonic waves) to the subject and the reception of the reflected acoustic waves (reflected ultrasonic waves) with respect to the transmitted ultrasonic waves, in addition to the detection of the photoacoustic waves. The transmission and reception of the sound waves may be performed at different positions. For example, ultrasonic waves may be transmitted from a position different from the position of the probe 11 and the probe 11 may receive the reflected ultrasonic waves with respect to the transmitted ultrasonic waves. The probe 11 is not limited to a linear probe and may be a convex probe or a sector probe.

The ultrasound unit 12 includes a receiving circuit 21, a receiving memory 22, data demultiplexing means 23, photoacoustic image generation means 24, ultrasound image generation means 25, image output means 26, a transmission control circuit 27, and control means 28. The ultrasound unit 12 forms a signal processing device. The ultrasound unit 12 typically includes a processor, a memory, and a bus. A program related to the generation of a photoacoustic image is incorporated into the ultrasound unit 12. The program is executed to implement the functions of at least some of the components in the ultrasound unit 12.

The receiving circuit 21 receives a detection signal output from the probe 11 and stores the received detection signal in the receiving memory 22. The receiving circuit 21 typically includes a low noise amplifier, a variable gain amplifier, a low-pass filter, and an analog-to-digital convertor (AD convertor). The detection signal from the probe 11 is amplified by the low noise amplifier. The gain of the detection signal is adjusted by the variable gain amplifier according to a depth and a high-frequency component of the detection signal is cut by the low-pass filter. Then, the detection signal is converted into a digital signal in the AD convertor and is stored in the receiving memory 22. The receiving circuit 21 includes, for example, one integral circuit (IC).

The probe 11 outputs a detection signal of the photoacoustic waves and a detection signal of the reflected ultrasonic waves. The AD-converted detection signals (sampling data) of the photoacoustic waves and the reflected ultrasonic waves are stored in the receiving memory 22. The data demultiplexing means 23 reads the sampling data of the detection signal of the photoacoustic waves from the receiving memory 22 and transmits the sampling data to the photoacoustic image generation means 24. In addition, the data demultiplexing means 23 reads the sampling data of the reflected ultrasonic waves from the receiving memory 22 and transmits the sampling data to the ultrasound image generation means (reflected acoustic image generation means) 25.

The photoacoustic image generation means 24 generates a photoacoustic image on the basis of the detection signal of the photoacoustic waves detected by the probe 11. The generation of the photoacoustic image includes, for example, image reconfiguration, such as phasing addition, detection, and logarithmic conversion. The ultrasound image generation means 25 generates an ultrasound image (reflected acoustic image) on the basis of the detection signal of the reflected ultrasonic waves detected by the probe 11. The generation of the ultrasound image includes, for example, image reconfiguration, such as phasing addition, detection, and logarithmic conversion. The image output means 26 outputs the photoacoustic image and the ultrasound image to image display means 16 such as a display device.

The control means 28 controls each component in the ultrasound unit 12. For example, in a case in which a photoacoustic image is acquired, the control means 28 transmits a trigger signal to the first light source 13 or the second light source 14 such that the first light source 13 or the second light source 14 emits laser light. In addition, the control means 28 transmits a sampling trigger signal to the receiving circuit 21 to control, for example, the sampling start time of the photoacoustic waves with the emission of the laser light.

In a case in which an ultrasound image is acquired, the control means 28 transmits an ultrasound transmission trigger signal for instructing the transmission of ultrasonic waves to the transmission control circuit 27. In a case in which the ultrasound transmission trigger signal is received, the transmission control circuit 27 directs the probe 11 to transmit ultrasonic waves. For example, the probe 11 performs scanning while shifting acoustic lines one by one to detect reflected ultrasonic waves. The control means 28 transmits a sampling trigger signal to the receiving circuit 21 in synchronization with the transmission of the ultrasonic waves to start the sampling of the reflected ultrasonic waves.

The control means 28 may switch the operation mode of the photoacoustic image generation apparatus 10 among three operation modes. In a first operation mode, the first light source 13 emits light with the first wavelength, the photoacoustic waves (first photoacoustic waves) generated from the light absorption member 51 are detected, and a photoacoustic image (first photoacoustic image) is generated. In a second operation mode, the second light source 14 emits light with the second wavelength, the photoacoustic waves (second photoacoustic waves) generated by the irradiation of the subject with the light with the second wavelength transmitted through the light absorption member 51 are detected, and a photoacoustic image (second photoacoustic image) is generated. In a third operation mode, ultrasonic waves are transmitted to the subject, ultrasonic waves reflected from the subject are detected, and an ultrasound image is generated. The user, such as a doctor, can select the operation mode using input means (not illustrated), such as a keyboard or a console switch. Alternatively, the three operation modes may be sequentially automatically switched and images obtained in each operation mode may be combined and displayed.

Then, the procedure of an operation will be described. FIG. 5 illustrates the procedure of the operation of the photoacoustic image generation apparatus 10. The operation mode selected by the user is stored in a variable mode. The control means 28 switches a process according to the variable mode (Step S1). In a case in which the variable mode is the first operation mode, the control means 28 performs a first photoacoustic image generation process in the photoacoustic image generation apparatus 10 (Step S2). In a case in which the variable mode is the second operation mode, the control means 28 performs a second photoacoustic image generation process in the photoacoustic image generation apparatus 10 (Step S3). In a case in which the variable mode is the third operation mode, the control means 28 performs a third photoacoustic image generation process in the photoacoustic image generation apparatus 10 (Step S4). The photoacoustic image generation apparatus 10 displays the image generated in Step S2, Step S3, or Step S4 on the image display means 16 (Step S5).

FIG. 6 illustrates the procedure of the first photoacoustic image generation process. The control means 28 directs the first light source 13 to emit light (Step S21). In Step S21, the control means 28 transmits a trigger signal to the first light source 13. In a case in which the first light source 13 is a solid-state laser device including a flash lamp and a Q-switch, the trigger signal includes, for example, a flash lamp trigger signal and a Q-switch trigger signal. In the first light source 13, the flash lamp is turned on in response to the flash lamp trigger signal and then the Q-switch is driven in response to the Q-switch trigger signal to emit pulsed laser light with the first wavelength. In a case in which the first light source 13 is a laser diode, a laser driver circuit makes a predetermined amount of current flow to the laser diode for the time corresponding to a pulse width in response to the trigger signal to emit pulsed laser light with the first wavelength.

The pulsed laser light emitted from the first light source 13 is incident on the optical fiber 19 through the optical fiber 17, the wavelength division multiplexing coupler 18, and the optical connector 20, is guided to the vicinity of the leading end of the puncture needle 15 by the optical fiber 19, and is emitted from the light emitting portion 19 a (see FIG. 2). At least a portion of the pulsed laser light is emitted to the light absorption member 51 provided at the leading end of the puncture needle 15. The light absorption member 51 absorbs the light with the first wavelength and generates photoacoustic waves (Step S22).

The probe 11 detects the photoacoustic waves generated by the emission of the laser light, that is, the photoacoustic waves (first photoacoustic waves) generated by the light absorption member 51 (Step S23). The photoacoustic waves detected by the probe are received by the receiving circuit 21 and the sampling data of the photoacoustic waves is stored in the receiving memory 22. The photoacoustic image generation means 24 receives the sampling data of the detection signal of the photoacoustic waves through the data demultiplexing means 23 and generates a photoacoustic image (first photoacoustic image) (Step S24). The photoacoustic image generation means 24 may apply a color map (Step S25) to convert the signal intensity of the photoacoustic image into a color. The photoacoustic image generated by the photoacoustic image generation means 24 is stored in, for example, an image memory (not illustrated) of the image output means 26 (Step S26).

FIG. 7 illustrates the procedure of the second photoacoustic image generation process. The control means 28 directs the second light source 14 to emit light (Step S31). In Step S31, the control means 28 transmits a trigger signal to the second light source 14. In a case in which the second light source 14 is a solid-state laser device including a flash lamp and a Q-switch, the trigger signal includes, for example, a flash lamp trigger signal and a Q-switch trigger signal. In the second light source 14, the flash lamp is turned on in response to the flash lamp trigger signal and then the Q-switch is driven in response to the Q-switch trigger signal to emit pulsed laser light with the second wavelength. In a case in which the second light source 14 is a laser diode, a laser driver circuit makes a predetermined amount of current flow to the laser diode for the time corresponding to a pulse width in response to the trigger signal to emit pulsed laser light with the first wavelength.

The pulsed laser light emitted from the second light source 14 is incident on the optical fiber 19 through the optical fiber 17, the wavelength division multiplexing coupler 18, and the optical connector 20, is guided to the vicinity of the leading end of the puncture needle 15 by the optical fiber 19, and is emitted from the light emitting portion 19 a (see FIG. 2). Since the light absorption member 51 covering thee light emitting portion 19 a transmits light with the second wavelength, the pulsed laser light with the second wavelength emitted from the light emitting portion 19 a is emitted from the opening of the puncture needle 15 to the subject. In a case in which an absorber that absorbs light with the second wavelength is present in the emission range of the pulsed laser light with the second wavelength, photoacoustic waves (second photoacoustic waves) are generated from the absorber (Step S32).

The probe 11 detects the photoacoustic waves generated by the emission of the laser light, that is, the photoacoustic waves (second photoacoustic waves) generated by the subject (Step S33). The photoacoustic waves detected by the probe are received by the receiving circuit 21 and the sampling data of the photoacoustic waves is stored in the receiving memory 22. The photoacoustic image generation means 24 receives the sampling data of the detection signal of the photoacoustic waves through the data demultiplexing means 23 and generates a photoacoustic image (second photoacoustic image) (Step S34). The photoacoustic image generation means 24 may apply a color map (Step S35) to convert the signal intensity of the photoacoustic image into a color. It is preferable that the color map used in Step S35 is different from the color map used to generate the first photoacoustic image. The photoacoustic image generated by the photoacoustic image generation means 24 is stored in, for example, the image memory (not illustrated) of the image output means 26 (Step S36).

FIG. 8 illustrates the procedure of the ultrasound image generation process. The control means 28 transmits an ultrasound trigger signal to the transmission control circuit 27. The transmission control circuit 27 directs the probe 11 to transmit ultrasonic waves in response to the ultrasound trigger signal (Step S41). The probe 11 transmits ultrasonic waves and detects reflected ultrasonic waves (Step S42). The reflected ultrasonic waves detected by the probe 11 are received by the receiving circuit 21 and the sampling data of the reflected ultrasonic waves is stored in the receiving memory 22. The ultrasound image generation means 25 receives the sampling data of the detection signal of the reflected ultrasonic waves through the data demultiplexing means 23 and generates an ultrasound image (Step S43). The ultrasound image generation means 25 may apply a color map (Step S44) to convert the signal intensity of the ultrasound image into a color. The ultrasound image generated by the ultrasound image generation means 25 is stored in, for example, the image memory (not illustrated) of the image output means 26 (Step S45).

The user can appropriately switch the operation mode between the first to third operation modes while inserting the puncture needle 15. For example, when starting the insertion of the puncture needle 15, the user selects the third operation mode and performs an operation such that an ultrasound image is displayed on the image display means 16. After starting the insertion, the user switches the operation mode to the first operation mode and performs an operation such that the first photoacoustic image is displayed on the image display means 16. In the first photoacoustic image, the position of the light absorption member 51 that absorbs light with the first wavelength and generates photoacoustic waves appears as a bright point. Therefore, it is possible to can check the position of the leading end of the puncture needle 15 with reference to the first photoacoustic image.

In a case in which the puncture needle 15 is inserted to a certain depth, the user switches the operation mode to the second operation mode and performs an operation such that the second photoacoustic image is displayed on the image display means 16. In a case in which a light absorber that absorbs light with the second wavelength is present in the vicinity of the leading end of the puncture needle 15 in the subject, the position of the light absorber appears as a bright point in the second photoacoustic image. For example, in a case in which the second wavelength is a wavelength absorbed by blood and blood is present in the vicinity of the leading end of the puncture needle 15, a bright point appears in the second photoacoustic image. The user can determine whether the puncture needle 15 has been inserted to the part in which blood is present, on the basis of whether a bright point is present. The photoacoustic image generation apparatus 10 may determine whether the sum of the signals of the second photoacoustic image is equal to or greater than a threshold value. In a case in which the sum is equal to or greater than the threshold value, the photoacoustic image generation apparatus 10 may notify the user of the determination result. The user may perform a needling operation while alternately switching the operation mode between the first operation mode and the second operation mode.

In the above description, the first photoacoustic image, the second photoacoustic image, and the ultrasound image are generated in the independent operation modes. However, the invention is not limited thereto. For example, at least one of the first photoacoustic image or the second photoacoustic image and the ultrasound image may be generated in one operation mode. In this case, the image output means 26 may function as image combination means for combining at least two of the first photoacoustic image, the second photoacoustic image, and the ultrasound image. The image output means 26 may combine the first photoacoustic image and the ultrasound image and display a composite image on the image display means 16. In addition, the image output means 26 may combine the second photoacoustic image and the ultrasound image and display a composite image on the image display means 16. Alternatively, the image output means 26 may combine the first photoacoustic image, the second photoacoustic image, and the ultrasound image and display a composite image on the image display means 16.

In this embodiment, the light with the first wavelength emitted from the first light source 13 and the light with the second wavelength emitted from the second light source 14 are selectively incident on the optical fiber 19 and light absorption member 51 is selectively irradiated with the light with the first wavelength and the light with the second wavelength. In a case in which the light absorption member 51 is irradiated with the light with the first wavelength, the light absorption member 51 generates photoacoustic waves and the first photoacoustic image is generated on the basis of the detection signal of the photoacoustic waves. The first photoacoustic image includes the positional information of the leading end of the puncture needle 15. In contrast, in a case in which the light absorption member 51 is irradiated with the light with the second wavelength, the light absorption member 51 transmits the light with the second wavelength and the light with the second wavelength is emitted from the leading end of the puncture needle 15 to the subject. In a case in which a light absorber is present in the part irradiated with the light with the second wavelength in the subject, photoacoustic waves are generated from the light absorber and the second photoacoustic image is generated on the basis of the detection signal of the photoacoustic waves. The second photoacoustic image includes surrounding environment information.

In this embodiment, the light absorption member 51 that absorbs light with the first wavelength, generates photoacoustic waves, and transmits light with the second wavelength without absorbing the light with the second wavelength is used. As such, the light absorption member 51 is used and is selectively irradiated with the light with the first wavelength and the light with the second wavelength. Therefore, it is possible to separately acquire the positional information and the surrounding environment information of the tip of the needle, using one puncture needle 15. In a case in which a wavelength that is absorbed by a material in the part to be needled to generate photoacoustic waves is selected as the second wavelength, it is possible to determine whether the puncture needle 15 has been inserted into the part to be needled, using the second photoacoustic image.

Here, in JP2013-13713A, it is difficult to separate the photoacoustic waves generated by the absorption of light emitted from the light emitting unit by a light absorber which is present in front of the needle in the needling direction in the subject from the photoacoustic waves generated by the absorption of light emitted from the light emitting unit by, for example, metal forming the puncture needle main body. Therefore, two bright points are mixed in the photoacoustic image. In some cases, since the intensity of the detected photoacoustic waves is sequentially changed by the movement of the body or the movement of the probe, a bright point blinks in the photoacoustic image. In JP2013-13713A, in a case in which a reduction in the brightness of the bright point occurs in the photoacoustic image, the operator needs to perform, for example, an operation of changing the position or angle of the ultrasound probe to reconfirm the position or angle of the probe at which the brightness is the maximum. That is, JP2013-13713A has the problem that the operator needs to perform an unnecessary operation. However, this embodiment has the advantage that, since positional information and surrounding environment information are separated, the above-mentioned problem does not occur.

Next, a second embodiment of the invention will be described. This embodiment differs from the first embodiment in that the puncture needle 15 further includes a phosphor. The phosphor is provided at the position that is irradiated with light emitted from the light emitting portion 19 a (see FIG. 2) and converts light with the second wavelength emitted from the light emitting portion 19 a into light with a third wavelength. The third wavelength is different from the first wavelength and the second wavelength. In this embodiment, in a case in which the second light source 14 emits light with the second wavelength, the subject is not irradiated with the light with the second wavelength, but is irradiated with the light with the third wavelength. The other configurations may be the same as those in the first embodiment.

It is preferable that the phosphor emits light, for example, in a nanosecond order. For example, a quantum dot or an organic phosphor (organic pigment) is used as the phosphor. It is preferable that the quantum dot is a PbS-based quantum dot. For example, a quantum dot manufactured by Evident Technologies Inc. is used. The phosphor is mixed with, for example, the light absorption member 51. Specifically, a light absorber that absorbs light with the first wavelength and transmits light with the second wavelength and the phosphor are mixed with a resin such as an epoxy resin. Alternatively, the light emitting portion 19 a may be covered with the resin having the phosphor mixed therewith and each resin having the phosphor mixed therewith may be covered with the resin having the light absorber mixed therewith. On the contrary, the light emitting portion 19 a may be covered with the resin having the light absorber mixed therewith and then may be covered with the resin having the phosphor mixed therewith.

The phosphor mixed with the light absorption member 51 varies depending on the puncture needle 15. For example, in a case in which there are a plurality of puncture needles 15, the wavelength of light emitted from the second light source 14 may be maintained to be the second wavelength and the wavelength of fluorescent light emitted from the phosphor may vary depending on the puncture needles 15. For example, the puncture needle 15 for blood includes a phosphor that converts light with the second wavelength into light with a wavelength of 530 nm. In contrast, the puncture needle 15 for a nerve includes a phosphor that converts light with the second wavelength into light with a wavelength of 1210 nm. In a case in which the part to be needled is a blood vessel, the puncture needle 15 for blood is used. In a case in which the part to be needled is a nerve, the puncture needle for a nerve is used. In this way, it is possible to select the target of which the surrounding environment information is to be evaluated, without changing the wavelength of light emitted from the second light source 14.

FIG. 9 illustrates the absorbance-wavelength characteristics of the phosphor. The horizontal axis indicates a wavelength and the vertical axis indicates absorbance. FIG. 9 illustrates the absorbance-wavelength characteristics of three PbS-based phosphors (quantum dots) represented by graphs a to c. As can be seen from FIG. 9, these phosphors have high absorbance in the wavelength range of about 400 nm to 500 nm. Therefore, it is preferable that a light source which emits light with a wavelength of 400 nm to 500 nm is used as the second light source 14. In a case in which the first wavelength is 905 nm, the phosphors represented by the graphs b and c absorb a certain amount of light and generate photoacoustic waves. However, the intensity of the generated photoacoustic waves is sufficiently lower than that of the photoacoustic waves generated from the light absorber of the light absorption member 51 and is as low as the level of noise, which causes no problem.

FIG. 10 illustrates the fluorescent emission intensity-wavelength characteristics of the phosphor. The horizontal axis indicates a wavelength and the vertical axis indicates emission intensity. FIG. 10 illustrates the emission intensity-wavelength characteristics of three PbS-based phosphors (quantum dots) represented by graphs a to c. The phosphor represented by the graph a generates fluorescent light with a wavelength of about 800 nm, using light with the second wavelength as excitation light. The phosphor represented by the graph b generates fluorescent light with a wavelength of about 1100 nm, using light with the second wavelength as excitation light. The phosphor represented by the graph c generates fluorescent light with a wavelength of about 1500 nm, using light with the second wavelength as excitation light. As such, it is possible to generate fluorescent light components with different wavelengths according to the phosphor used, while maintaining the second wavelength.

In this embodiment, the puncture needle 15 includes the phosphor that converts light with the second wavelength into light with the third wavelength. In this case, the photoacoustic waves generated by the emission of the light with the third wavelength are detected and the second photoacoustic image is generated on the basis of the detection signal of the photoacoustic waves. In this way, it is possible to evaluate the surrounding environment of the leading end of the puncture needle 15. In this embodiment, the phosphor used is changed to change the wavelength of fluorescent light. Therefore, even in a case in which there are a plurality of evaluation targets, it is not necessary to prepare light sources that emit light components with a plurality of wavelengths. As a result, it is possible to prevent an increase in the overall cost of the apparatus. The other effects are the same as those in the first embodiment.

Next, a third embodiment of the invention will be described. This embodiment differs from the first and second embodiments in that the puncture needle 15 includes an outer needle and an inner needle. The other configurations may be the same as those in the first embodiment or the second embodiment.

FIG. 11 is a cross-sectional view illustrating a puncture needle 15 a according to this embodiment. A puncture needle main body 151 forming the outer needle has an opening at an acute leading end and has an inner cavity. An inner needle 152 has substantially the same inside diameter as the inner cavity of the puncture needle main body 151 and is configured so as to be inserted into or removed from the hollow puncture needle main body 151. The inner needle 152 is inserted into the inner cavity of the puncture needle main body 151 from the base end side of the puncture needle main body 151 to seal at least a portion of the inner cavity of the puncture needle main body 151 to the extent that, for example, a section of the living body is prevented from being inserted into the inner cavity. A protruding portion for connection position adjustment is provided in a base end portion of the inner needle 152. A groove into which the protruding portion provided in the base end portion of the inner needle 152 is fitted is provided in a base end portion of the puncture needle main body 151. In a case in which the inner needle 152 is set in the puncture needle main body 151, the protruding portion provided in the base end portion of the inner needle 152 and the groove provided in the base end portion of the puncture needle main body 151 are positioned and the base end portion of the inner needle 152 is fitted to the base end portion of the puncture needle main body 151.

The inner needle 152 includes the optical fiber 19, the light absorption member 51, a tube 158, and a transparent resin 159. The tube 158 is, for example, a hollow tube made of polyimide. The tube 158 may be a metal tube made of, for example, stainless steel. The outside diameter of the tube 158 is slightly less than the diameter of the inner cavity of the puncture needle main body 151. The transparent resin 159 is provided in the tube 158. For example, an epoxy resin (adhesive) is used as the transparent resin 159. The tube 158 and the transparent resin 159 are acute, similarly to the acute leading end of the puncture needle. A photocurable resin, a thermosetting resin, or a room-temperature-curable resin may be used as the transparent resin 159.

The optical fiber 19 is covered with the transparent resin 159 in the tube 158. The light absorption member 51 is provided at the leading end of the optical fiber 19. The light absorption member 51 is irradiated with the light emitted from the light emitting portion 19 a. The light absorption member 51 may further include the phosphor described in the second embodiment. In a case in which the first light source 13 (see FIG. 1) emits light, the light absorption member 51 absorbs the emitted light with the first wavelength and photoacoustic waves are generated at the leading end of the puncture needle.

An operator, such as a doctor, inserts the puncture needle 15 a into the subject, with the inner needle 152 set in the puncture needle main body 151. Since the inner cavity of the puncture needle main body 151 is closed by the inner needle 152, it is possible to prevent a piece of flesh from getting into the needle while the needle is being inserted and thus to prevent the needling sense of the operator from being hindered. In addition, it is possible to prevent the inflow of water from the part to be needled to the inner cavity of the puncture needle main body 151. After inserting the needle into the subject, the operator releases the connection between the base end portion of the inner needle 152 and the base end portion of the puncture needle main body 151 and takes the inner needle 152 out of the puncture needle main body 151. After taking the inner needle 152 out of the puncture needle main body 151, the operator can attach, for example, a syringe to the base end portion of the puncture needle main body 151 and inject a medicine such as an anesthetic.

In addition, the transparent resin 159 may close at least a leading end portion of the tube 158 and does not necessarily close the entire inside of the tube 158. FIG. 12 is a cross-sectional view illustrating the vicinity of the leading end of a puncture needle according to a modification example. In a puncture needle 15 b, a transparent resin 159 covers the light absorption member 51 covering the light emitting portion 19 a of the optical fiber 19 and (the leading end portion of) the optical fiber 19 and the light absorption member 51 are fixed to the inner wall of the tube 158 by the transparent resin 159. In addition, the transparent resin 159 closes an opening provided in the leading end portion of the tube 158. In a case in which this configuration is used, it is also possible to prevent the inflow of, for example, water into the inner needle 152.

The optical fiber 19 does not need to be fixed to the inner wall of the tube 158 by the transparent resin 159 and may be fixed to the inner cavity of the tube 158 by the light absorption member 51. The leading end portion of the tube 158 may be closed by the light absorption member 51. In this case, the transparent resin 159 may be omitted. In addition, instead of covering the optical fiber 19 with the transparent resin 159, the optical fiber 19 may be covered with a resin with which at least one of the light absorber described in the first embodiment or the phosphor described in the second embodiment.

In this embodiment, the puncture needle 15 a includes the inner needle 152 provided in the inner cavity of the puncture needle main body 151. The inner needle 152 closes the inner cavity of the puncture needle main body 151 while the puncture needle 15 a is being inserted. Therefore, it is possible to prevent the needling sense of the operator from being hindered and to prevent the inflow of water from the part to be needled to the inner cavity of the puncture needle main body 151. The other effects are the same as those in the first embodiment or the second embodiment.

In the above-described embodiments, the puncture needle 15 is considered as an insert. However, the invention is not limited thereto. The insert may be a radio frequency ablation needle including an electrode that is used for radio frequency ablation, a catheter that is inserted into a blood vessel, or a guide wire for a catheter that is inserted into a blood vessel. Alternatively, the insert may be an optical fiber for laser treatment.

In the above-described embodiments, a needle having an opening at the leading end is assumed as the needle. However, the opening is not necessarily provided at the leading end of the needle. The needle is not limited to an injection needle and may be a biopsy needle used for biopsy. That is, the needle may be a biopsy needle that is inserted into an inspection target of the living body and extracts the tissues of a biopsy site of the inspection target. In this case, photoacoustic waves may be generated from an extraction portion (intake port) for sucking and extracting the tissues of the biopsy site. In addition, the needle may be used as a guiding needle that is used for insertion to a deep part, such as a part under the skin or an organ inside the abdomen.

The puncture needle 15 is not limited to the needle that is inserted from the outside of the subject into the subject through the skin and may be a needle for ultrasound endoscopy. The optical fiber 19 and the light absorption member 51 may be provided in the needle for ultrasound endoscopy. The light absorption member 51 provided in the leading end portion of the needle may be irradiated with light with the first wavelength and light with the second wavelength while the light with the first wavelength and the light with the second wavelength are being switched. Photoacoustic waves may be detected and photoacoustic images (the first photoacoustic image and the second photoacoustic image) may be generated. In this case, it is possible to perform needling while observing the first photoacoustic image and checking the position of the leading end portion of the needle for ultrasound endoscopy. In addition, it is possible to determine whether an evaluation target material is present in the vicinity of the needle, using the second photoacoustic image. The first photoacoustic waves generated from the leading end portion of the needle for ultrasound endoscopy and the second photoacoustic waves generated from the vicinity of the leading end portion may be detected by a probe for body surface or a probe that is incorporated into an endoscope.

In the third embodiment, the example in which the inner needle 152 (see FIG. 11 or FIG. 12) includes the tube 158 has been described. However, the invention is not limited thereto. Instead of the configuration in which the tube 158 is used and the optical fiber 19 is covered with the transparent resin 159 in the tube 158, the optical fiber 19 that has an outside diameter substantially equal to the inside diameter of the puncture needle main body 151 may be used as the inner needle. Alternatively, an optical fiber that is coated with polyimide or a resin, such as a fluoride resin or an acrylic resin, in advance may be used.

The invention has been described above on the basis of the preferred embodiments. However, the photoacoustic image generation apparatus and the insert according to the invention are not limited to the above-described embodiments. Various modifications and changes of the configurations according to the above-described embodiments are also included in the scope of the invention. For example, the wavelength division multiplexing coupler 18 is used as a detailed configuration for transmitting light with the first wavelength and light with the second wavelength to the optical fiber 19 while switching the light with the first wavelength and the light with the second wavelength. However, the invention is not limited thereto. A plurality of optical fibers 17 that guide light emitted from a plurality of light sources are arranged and a switch member that aligns the position of the end of the optical fiber 19 connected to the leading end of the puncture needle with the position of the end of one of the plurality of optical fibers 17 is appropriately used. 

What is claimed is:
 1. An insert that is at least partially inserted into a subject, comprising: a light guide member that guides light with a first wavelength and light with a second wavelength different from the first wavelength which are incident while being switched; a light emitting portion from which the light guided by the light guide member is emitted; and a light absorption member that absorbs the light with the first wavelength emitted from the light emitting portion, generates photoacoustic waves, and transmits the light with the second wavelength emitted from the light emitting portion.
 2. The insert according to claim 1, wherein the light absorption member covers at least a part of the light emitting portion.
 3. The insert according to claim 1, wherein the light absorption member includes a light absorber that absorbs the light with the first wavelength and transmits the light with the second wavelength and a resin including the light absorber.
 4. The insert according to claim 1, wherein: the insert has an inner cavity; and the light absorption member functions as a fixing member that fixes the light guide member to an inner wall of the inner cavity.
 5. The insert according to claim 1, further comprising a transparent resin that transmits at least the light with the second wavelength, wherein the light absorption member is covered with the transparent resin.
 6. The insert according to claim 5, wherein: the insert has an inner cavity; and the light guide member and the light absorption member are fixed to an inner wall of the inner cavity by the transparent resin.
 7. The insert according to claim 1, wherein the insert is a puncture needle having an inner cavity; and the insert further includes a hollow tube in which the light guide member is accommodated.
 8. The insert according to claim 7, wherein: the puncture needle includes an inner needle and an outer needle; the inner needle includes the hollow tube; and the inner needle seals at least a portion of the inner cavity.
 9. The insert according to claim 7, wherein the light absorption member functions as a fixing member that fixes the light guide member to an inner wall of the hollow tube.
 10. The insert according to claim 7, further comprising a transparent resin that transmits at least the light with the second wavelength, wherein the light guide member and the light absorption member are fixed to an inner wall of the hollow tube by the transparent resin.
 11. The insert according to claim 1, further comprising a phosphor that converts the light with the second wavelength emitted from the light emitting portion into light with a third wavelength different from the first wavelength and the second wavelength.
 12. The insert according to claim 1, further comprising an optical connector that detachably connects the light guide member and an optical fiber which guides the light with the first wavelength and the light with the second wavelength emitted from a light source.
 13. A photoacoustic image generation apparatus comprising: a first light source that emits light with a first wavelength; a second light source that emits light with a second wavelength different from the first wavelength; an insert that is at least partially inserted into a subject and comprises a light guide member that guides the light with the first wavelength and the light with the second wavelength which are incident while being switched, a light emitting portion from which the light guided by the light guide member is emitted, and a light absorption member that absorbs the light with the first wavelength emitted from the light emitting portion, generates photoacoustic waves, and transmits the light with the second wavelength emitted from the light emitting portion; acoustic wave detection section for detecting first photoacoustic waves which are generated by the absorption of the light with the first wavelength by the light absorption member and second photoacoustic waves which are generated in the subject due to the light emitted from the light emitting portion; and photoacoustic image generation section for generating a first photoacoustic image on the basis of the first photoacoustic waves and generating a second photoacoustic image on the basis of the second photoacoustic waves.
 14. The photoacoustic image generation apparatus according to claim 13, wherein the second photoacoustic waves are generated by the absorption of the light with the second wavelength transmitted through the light absorption member by the subject.
 15. The photoacoustic image generation apparatus according to claim 13, wherein the insert further includes a phosphor that converts the light with the second wavelength emitted from the light emitting portion into light with a third wavelength different from the first wavelength and the second wavelength; and the second photoacoustic waves are generated by the absorption of the light with the third wavelength emitted from the phosphor by the subject.
 16. The photoacoustic image generation apparatus according to claim 13, wherein: the acoustic wave detection section further detects reflected acoustic waves with respect to acoustic waves transmitted to the subject; and the photoacoustic image generation apparatus further comprises reflected acoustic image generation section for generating a reflected acoustic image on the basis of the reflected acoustic waves.
 17. The photoacoustic image generation apparatus according to claim 16, further comprising: image combination section for combining at least one of the first photoacoustic image or the second photoacoustic image and the reflected acoustic image. 